Ball of light travelling in straight line over Lincolnshire in the clear night sky

It was a very clear night at twilight and we saw a light coming towards us assuming it was a helicopter. But as it came nearer it was just like a ball of orange-ish light with a haze of light around it. There was no sound at all and it travelled in a straight line anywhere between 2000 and 4000 feet above us. As it travelled over us the light then disappeared but one witness saw just a silhouette of the sphere. Two other witnesses had said that they had seen similar the night before, but 4 or 5 of the lights. One witness estimated that it travelled about 120 kts.